Thermostatic control mechanism



May 13, 1941. J. A. CERNY 2,241,930

THERMOSTATIC CONTROL MECHANISM Filed Nov. 15, 1957 FIG. 3

FIG-5 INVENTOR JOSEPH A. CERNY BY %g41474=/ ATTORNEYS Patented May 13, 1941 UNITED STATES PATENT OFFICE 2,241,980 THERMOSTATIC CONTROL MECHANISM Joseph A. Cerny, Cleveland, Ohio, assignor to The Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application November 13, 1937, Serial No. 174,306 Claims. (01? 236-48) Titan Valve and This invention relates to improvements in thermostatic control devices and more particularly to an improved device permitting a very nice adjustment of temperature range.

An object of the present invention is the provision between a thermostatic element and a control member operable thereby of a lever enotally mounted support wherein the leverage provides an operative connection between a thermostatic element and a control member operated thereby, together with-means for adjusting the support to various positions about its pivot for the purpose of varying the temperature which the control mechanism is intended to maintain.

In the specific embodiment herein disclosed. my invention provides a pivotaliy supported frame having two levers supported thereon and connected by a spring in such a manner that movement of one of the levers carries the spring from side to side of the fulcrum of the other lever whereby to produce a snap action control "and a lever arm for adjustably positioning the supporting frame about its pivot so as to vary the action of the levers. Preferably the adjustment of the supporting frame about its pivot comprises a threaded member having suflicient everage with reference to the pivotal mounting of the supporting frame to provide a very fine adjustment of the radial position of the fram about its pivot. 1

Other novel features of my improved device will be set forth in the specification and illustrated in the drawing and the essential features will be summarized in the claims.

In the drawing Fig. 1 is a sectional view of a thermostatic control mechanism embodying my device; Fig. 2 is a partial sectional view of the same mechanism showing the parts in a different position; While Figs-3, 4 and 5 are deta l perspective views of several parts of the lever mechanism.

I have illustrated my improved control mechanism as associated with a well known type of valve mechanism and associated parts adapted for use with gas fired devices. In the form shown, a casing or casting iil is arranged with suitable gas passages therethrough including a threaded connection for'gas inlet at H and a threaded connection for gas outlet'at I2. A main gas valve known to the trade as the A valve is indicated at l3 and a "13 valve or pilot valve at I 4. In an intermediate partition la is provided a gas port I 5 which is closable by the spring pressed valve IS. The spring I! normally urges the valve to closed position. A thermostatic element It is adapted to enter the casing to cooperate with the control mechanism for the opening and closing of valve IS in response to the temperature of the thermostatic element. The element shown comprises a tube l8a having a relatively large coefiicient of expansion. To the outer end of this tube is secured a rod [81) having a relatively small coefiicient of expansion; It results therefore when the thermostatic The control mechanism operatively connecting the thermostat i8 and the valve l6 comprises a multiple leverage carried by the support ID by a pivotal mounting 20 between the members Ill and i9. Preferably," as shown in the various views, the upper portion of the member i9 is generally. U-shape in form having pinreceivlng openings for the pin 20 at the points 20a. extending downwardly and struck up between them is the portion l9b. Member I9 is normally stationary, i. e., it does not move during ordinary operation of the parts. However, it is adjustable about its pivot to vary the mean temperature which the control .mechanism is intended to maintain, for which purpose, in the form shown, portion I9!) is engaged and held by adjusting member M which is threaded at 22 in a boss 23 of the casing ill and is provided at its outer end with an operating knob 24. The knob 24 is graduated on its face to coact with a fixed pointer 25a on easing ill. Pivotally mountedon the upper end of the member l9 by pin 25 is a main lever zfi. This lever is adapted to engage with the thermostat rod [8b at the point 21. This point is accurately fixed in the main lever by a small depression which receives the sharpened end of rod l8b. At the lower end of support ill at points 28 are fulcrumed the bifurcated legs 29a of a lever 29. As shown in the drawing, the lower ends of the legs 29a are provided with knife edges which rest in suitably formed grooves in the inwardly turned ends of l9 -which is adjustably mounted within the casing The member l9 has bifurcated legs 19a the legs I911. The upper end 2912 of the lever 29 passes through an opening I90 in the support i9 and is positioned to engage the end of valve l6. It will be noted that levers 26 and 29 are pivoted at opposite ends of the member i9 and 'extend generally toward each other. A spring 30 is connected between the free ends of levers 26 and 29 in such a manner that the spring is carried from side to side past the fulcrum 28 upon movement of lever 26 in response to the thermostatic element.

With the parts in the position of Fig. 1, the

tube I8a of ,the thermostatic element has ex-.

panded because of the temperature rise until the rod l8b has moved to the right, lever 26 moves to the right under the influence of spring 30 carrying the axis of the spring to the right of point 28 and snapping lever 29 to the right thus permitting valve I6a to close and cutting off the fuel to the heater burner. Upona cooling of the tube |8a it changes by contraction to a greater extent than the rod l8b, moving the I rod lab toward the left as viewed in Figs. 1 and 2, causing lever 26 to move in a clockwise direccomes heated,.causing'rod i8b to move to the right, moving spring 30 again to the position of Fig. 1, whereupon lever 29 returns in a clockwise direction permitting valve IE to close.

A very fine adjustment of the temperature range of my improved control device is provided in the structure shown. It will be noted that the distance between the point 2la where member 2| engages I91) and the point 20 is much greater than the distance from the point 21 to pivot and shiftable about that pivot tovary its relation to the thermostat. Also note that there is no packing necessary on the thermostat rod, thus leaving it perfectly free to find its own position. This is made possible because the adjusting member is located at the point 23 where the adjusting member can. be brought out of the casing Ill through an opening whichmay'be suitably packed as by the packing 3i held in place by a gland and this packing does not afiect the action of the thermostatic device. In other words this is .the only opening through the casing to permit of adj ustment and it is arranged at a point where a manually operable part extends through the casing so that the packing does not afl'ect the working of the device but is easily overcome at the time any adjustment is made by the hand of the operator on the knob 24.

My improved thermostatic device is so constructed and arranged that I am enabled to manufacture the parts to exact size and dimensions and assemble them in exact relationship very simply so that in mass production of these devices each one will be exactly like the others and easily adjustedto exact operating conditions. This is made possible because all of the operating leverage issuspended from pivot 20 and in the manufacture of the device the points in casing in supporting the pin 20 may be jigged in exact relation to the valve opening I5. The point 21 is exactly located on the lever 26 as pointed out previously by the formation of a slight depression. Also pin 25 may be exactly positioned with reference to pin 20 as will be readily apthe point 20, in fact it is over three times as this isan adjustment of the range of'action of the thermostat and determines'the mean temperature which the control mechanism is intended to maintain. This adjustment has nothing to do with the sensitivityor diflerential of the device which is set when the device'is manui'actured. This permits a very fine adjustment foi the distance between lever 28 and thermostatically actuatedrod 'I8b. at the point 21.

Such an adjusting movement in combination with the above I provide a fine adjusting thread between the member 2| and the, boss 2 3, I then arrange for a fine adjustment of the position of thearm i9bwhich through .the relationship between the arms 2la20 and 21-20 just referred to, gives an even finer adjustment at the point 21. The adlusting knob'24 may be suitably marked to indicate the temperature ranges when the device the length of the thermostat rod and easily accessible.

It-will be noted that with the improved constructionhere disclosed there is no adjustment parent from Fig. 4. Thus I have arranged a device which comprises buta fewparts, all of which may be exactly manufactured and when assembledwill be in a definite fixed relationship.

It will be noted that the line of action of the spring force exerted by spring 30 always extends to the right of pivots 20 and 25 as seen in Figs. 1 and 2. Thus when lever 26 is in contact with rod lab, spring 30 tends in two ways to turn lever l9 in a clockwise direction to. hold that level.

against adjusting member 2i. The downward thrust of lever 29 against lever 19 exerts one turning force and the tendency of the spring to turn lever 26 counterclockwiseabout point 21 tends to move .pivot 25' and lever l9 clockwise about pivot 20.

What I claim is:

1. Control mechanism of the class described,

comprising the combination with a casing, of a. control member, ,a thermostat, and snap acting operating 'mechanism connecting said member and thermostat, including three levers supported in said casing" and lying generally parallel with each other, one lever forming a support and beingliulcrumed near one end to enable it tcbe set in various positions, a second lever being actuated by the thermostat and being fulcrumed to the support lever at a point spaced lengthwise of the support lever from its fulcrum, said first and second levers extending in the same direction from their respective i'ulcrurns', a third lever being arranged to operate'the' control member and being fulcrumed'on'the free end of the first lever and extending toward the first lever 'ful crum, and a tension spring connecting the free ends of said second and third levers.

2. Control mechanism of the class described,. comprising the combination with a casing, of a control member, a thermostat, and snap acting operating mechanism connecting said member and thermostat, including three levers supported in said casing andlying generally parallel with each other, one lever forming a support and being fulcrumed near one end to enable it to be set in various positions, a second lever being engaged and actuated by the thermostat. and being fulcrumed to the first named lever at a point 'between said thermostat engaging point and the fulcrum of said first named lever, said first and second levers extending in the same direction from their respective fuicrums, the third lever being arranged to operate the control member and being fulcrumed on the free end of the first named lever and extending toward the fulcrum of said first named-lever, and a tension spring connecting the free ends of said second and third levers.

3. Control mechanism of the character described in claim 1, including means for adjusting the first lever about its fulcrum to thereby adjust the fulcrum of the second lever transversely to the length of the second lever and thus vary ,the'mean temperature which the control mechanism is designed to maintain.

4. Control mechanism of the character described in claim 2, including means for adjusting the first lever about its-fulcrum to thereby adjust the fulcrum of the second lever transvary the mean temperature which the control mechanism is designed to maintain.

5. Control mechanism of-the class described,

comprising the combination with a casing, of a control member, a thermostat, and snap actin operating mechanism connecting said member and thermostat, including three levers supported in said casing and lying generally parailelwith each other, one lever forming a support and being fulcrumed near one end to enable it to beset in various positions, a second lever being. actuated by the thermostat and being fulcrumed-to the support lever'at a point spaced lengthwise of the support lever from its fulcrum, said first and second levers extending in the same direction from their respective fulcrums, a third lever being fulcrumed at one end and arranged to operate the control member, the free end of said third lever extending toward the first lever fulcrum, a tension spring having one of its ends connected with the free end of said third lever. and the fulcrum of said third lever and the other end of said spring being carried one'by said first lever and one by said second lever.

JOSEPH A. CERNY. 

